78 INSECUTOR INSCITI.5; MENSTRUUS 



pools filled by overflow from high water of rivers. There is 

 usually a single spring generation in the north (adults, April, 

 at Washington, D. C. ; June, at Ottawa, Ontario, and Fort 

 Snelling, Minnesota), but in the south the emergence seems to 

 depend upon casual floods, which may not recur for a period 

 of years. Specimens before me from Wister, Indian Terri- 

 tory, were taken in July, and Mr. E. W. Jackson of the Essex 

 County Mosquito Extermination Board in New Jersey told 

 me of an experience of his where a flood occurred in the valley 

 of a river. He watched successive broods of hirsuteron ap- 

 pearing in higher and higher pools as the water was backed 

 up farther from week to week, until finally pools were reached 

 which had not been water-filled for twelve years preceding, 

 yet hirsuteron larvae appeared in them. Mr, Jackson asked me 

 how long the eggs could live on the ground, a question more 

 easy to ask than to answer. 



Species 11. 



Aedes (Ochlerotatus) aestivalis Dyar (PI. I, fig. 6). 



Culex reptans Dyar (not Linnaeus), Proc. Ent. Soc. Wash., vi, 



38, 1904. 

 Culex aestivalis Dyar, Journ. N. Y. Ent. Soc, xii, 245, 1904. 

 Grabhamia aestivalis Dyar, Proc. Ent. Soc. Wash., vii, 48, 1905. 

 Grabhamia aestivalis Dyar, Journ. N. Y. Ent. Soc, xiii, 54, 1905. 

 Aedes aestivalis Dyar & Knab, Journ. N. Y. Ent. Soc, xiv, 201, 



1906. 

 Ochlerotatus aestivalis Coquillett, U. S. Dep. Agr., Bur. Ent.. 



Tech. Ser. 11, 21, 1906. 

 Ochlerotatus aestivalis Dyar, U. S. Dep. Agr., Bur. Ent., Circ 



72, 6, 1906. 

 Aedes aestivalis Cameron, Agr. Gaz. Can., v, 557, 1918. 

 Aedes aestivalis Cameron, Journ. Am. Med. Vet. Ass., liii, 6.33, 



1918. 

 Aedes aestivalis Dyar, Ins. Ins. Mens., viii, 18, 1920. 



Slight larval differences have been observed between this 

 form and hirsuteron, but the matter is insufficiently investigated. 

 The form seems to be addicted to the vicinity of lakes rather 

 than rivers, and probably breeds in pools filled by high water 

 in spring. Some of the lakes in the mountains of the west rise 



